X4

X4, X-4 or x4 may refer to:


 * BMW X4, a German crossover automobile
 * Sehol X4, a Chinese crossover automobile
 * Honda X4, a Japanese motorcycle
 * Moto X4, an Android Smartphone
 * Mega Man X4, a video game
 * Naish X4, a kitesurfing kite
 * The Norteños street gang
 * Northrop X-4 Bantam, an early jet age research aircraft
 * A common name for petroleum ether
 * A four-lane PCI Express slot
 * Ruhrstahl X-4, a German World War II air-to-air guided missile
 * Ultimate X4, a comic-book crossover in the Ultimate Marvel Universe
 * X4 (New York City bus), an express bus route
 * Stagecoach Gold bus route X4, a bus route in the United Kingdom
 * X4 virus, a T-cell tropic HIV
 * X-Men Origins: Wolverine, a 2009 film
 * X-Men: Days of Future Past, a 2014 film
 * WordPerfect X4, a version of word processing software
 * X4: Foundations, a 2018 video game